Bacterial infections are the cause for about a quarter of the human deaths throughout the world. For example, in the U.S.A. in the early 2000s, food-borne bacteria were the reason for about 33,000,000 illnesses per year, of which about 10,000 were fatal.
Accessible and inexpensive methodologies for fast detection and identification of bacterial species are essential for prevention and early diagnosis. Polymerase chain reaction (PCR), immunoassays, fluorescence in situ hybridization, Raman spectroscopy and impedance spectrometry are some of the methodologies used for bacterial sensing. Optical techniques based on staining of bacterial cells with fluorescent dyes have gained immense popularity due to their: (1) relative simplicity; (2) relatively high sensitivity; (3) speed of analyses; and (4) low reagent cost.